Method and anode for electrodeposition of rust-resisting coatings



Patented Oct. 6, 1925.

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ROESSLER & HASSLACHEB CHEMICAL CQKPANTYQOF YORK, N. Y., A COR- mnrnon AND Axons ron. nnncrnonnrosrrxon or nusr-nnsrsrme confines.

No Drawing. Original application filed January-5, 1924, Serial No. 684,506. Divided and this application fled July 6, 1825. Serial llo. 4 1,866.- T

To all whom it may cmwem:

Be it known that I, CHRISTIAN JoHN WERNLUND, a citizen of the United S and resident of Totte-nville, in the county 0 5 Richmond and State of New York, have invented certain new and useful Improvements in Methods and Anodes for Electrodeposition of Rust-Resisting Coatings, of which the following is a specification.

mium, this application being a division of my application Serial I No. 684,506, filed January 5, 1924. Cadmium has many properties which render it advantageous over other metals and alloys as a protective coating for metals such as iron and steel. It is light in color and has a hi her solution potential than iron, thus tending to protect the iron from corrosion. As its solution potential is higher than that of iron and lower than that of zinc, the same weight of protective coating of cadmium aifords more protection to atmospheric corrosion than is afforded by straight zinclk Also more cadmium than zinc can be deposited per unit ofcurrent used. The oxide coating formed by atmospheric or other corrosionof cadmium is thinner and more adherent than that formed on zinc, conse%uently the tendency 0 of cadmium to scale and waste away is much less pronounced than that of zinc.

While I have found that pure cadmium 1 coatings can be effectively deposited electrolytically, I have further .found that alloy coatings comprising cadmium retain; in

0 large measure the advantageous features of rapidity of deposit and can be much more cheaply and conveniently produced than previous coatings of pure cadmium. Ac-

4 cording to-my invention, I produce alloyed and another metal, such as cadmium and 'mercury or zinc, or. zinc, cadmium 'and' This invention relates in generalv to the electroplating on iron and steel or other metal articles of alloys of zinc and cadpure cadmium coatings in durability and coatings comprising over 2% of cadmium I 1 g .in givininbetter protection than zinc with less the ess, good. color of coating, and economy of current.

Such a coatin of a platin so addition 0 cadmium or cadmium and T (zinc) compounds soluble in the'bath have the'ien made, or the metals can be furnished anodes and zinc anodes or alloy anodes.

Examples of the scope of this invention are as follows:

To plate wire screen; with a. zinc cadmium alloy, the material is cleaned by an alkaline electric cleaner or when rusty by alternate acid and alkaline clean metallicsurface is secured. The wire play then be plated in the following solu- Water 1 1 gal. Sodium cyanide 45 G. Y 6 oz. Sodium hydroxide 30 G. 4 oz. Zinc cyanide 30 G. 4 oz. Cadmium hydrate 7.5 G. 1 oz.

Other conditionsmaintained as fol- I lows 'Tenniperature 25 (77 F.)

(15]. F ""3 to 6volls.

urrent 25 am. res r aft.

Anodes' ZincQ Pe Sq The bath must be replenished from time to time as the several ingredients become depleted. An average analysis of the resulting coating will be 'miu'm 25-30%.

' Ewamplell.

I have also found that the zinc and cad- .mium contents of the bath may bestabi'lize'd by using zinc cadmium alloy anodes tosupply the desired quantities oft-hose metals to the solution. such an alloy an is Per cent.

may be formed by the use 1 ution .to which the proper the solution by the use of cadmium pickling until a chemicallyzinc 70-75%, cad

A 0dpreferred composition of Zinc 75 Cadmium J that in this case I In plating, for example, wire screen, I proceed as in example I with the exception substitute the zinc cadmium in place of the straight zincanodes.

In all the above examples the plating has been "done 'in a still bath. It is understood that if mechanical solutions are used such as in barrel plating the concentrations of solutions, currents required, etc., may be changed considerably-to conform to the different operating conditions.

I do not claim specifically herein the novel products resulting from the processes and aths herein disclosed, as such products are claimed in another application, Serial No.

684,507, filed January 5, 1924, patented Dec.

What I claim is;

1. Method of electrodepositing a rust-resistant deposit of cadmium and zinc Which consists in electrodepositing these metals from a solution of their salts in an aqueous sodium cyanide-sodium hydroxide solution.

2. Method of electrodepositing a rust resistant deposit of cadmium and zinc which consists in electrodepositing these metals from a solution of their salts in an aqueous sodium cyanide-sodium hydroxide solution wherein the article receivlng the deposit is the cathode and an alloy of cadmium and zincis the anode, 3. In zinc electroplating from a cyanide bath the step which consists in depositing zinc'in the resence of cadmium to roduce a coating 0% zinc allo ed with cadmium.

4. In zinc electropl ating from a cyanide bath, the step which consists in depositing zinc-in the presence of cadmium to produce a coating of zinc alloyed with a minor percentage of cadmium.

- 5. In zinc electroplating'from a cyanide bath, the step which consists in depositing I zinc in the'presence of cadmium to produce a coating of zinc alloyed withmore than 2% of cadmium, v

6. In plating ferrous articles with zinc from cyamde' baths, the improvement which being at least Middlesex and tion with the zinc,

7. In zinc electroplating from a cyanide bath, the step which consists in depositing zinc in the presence of a cadmium salt to produce a coating of'zinc alloyed with cadmium. p I

8.- In zinc-electroplating from a cyanide bath, the step which consists in depositing zinc in the presence of a salt ofcadmium to produce a coating of .zinc alloyed with a minor percentageof cadmium. I r

9. Method of electrodepositing an allo coating comprising zinc and cadmium which consists in makinglthe article to be plated the cathode and providing an anode comprisin zinc and cadmium.

10. ethod of electrodepositing an alloy coating comprising zinc and cadmium which consists in making the article to be plated the cathode and providing an anode contain- 7 ing zinc and cadmium, the cadmium content 11. The method of electrodepositing an alloy coating comprising zinc and cadmium which (consists in maln'ng the article to be plated the cathode and providing an anode whose major constituent is zinc and whose minor constituent is cadmium;

12. The method of electrodepositing an alloy coating comprising zinc and cadmium which consists in making the article to be plated the cathode and providing ananode whose major constituent is zinc and Whose minor constituent is at least 2% of cadmium.

13. An anode for electroplating comprising zinc and cadmium in amounts effective;

for the purpose set forth.

14. An anode for electroplating oomprisand cadmium in which the cading zinc mium content shall be above 2% and the zinc content above 10%. p

Signed at Perth Amboy, in the county of 29th day of June A. D. 1925.

CHRISTIAN JOHN WERNLUND.

State of New Jersey, this 

